Only a few genetic changes were enough to turn an ordinary stomach bug into the bacteria responsible for the plague.
The Mutant Genes Behind the Black Death
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Originally Posted by Quanta Magazine
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Now researchers are beginning to reveal a surprising genetic history of the plague. A rash of discoveries show how just a small handful of genetic changes — an altered protein here, a mutated gene there — can transform a relatively innocuous stomach bug into a pandemic capable of killing off a large fraction of a continent.
The most recent of these studies, published in June, found that the acquisition of a single gene named pla gave Y. pestis the ability to cause pneumonia, causing a form of plague so lethal that it kills essentially all of those infected who don’t receive antibiotics. In addition, it is also among the most infectious bacteria known. “Yersinia pestis is a pretty kick-ass pathogen,” said Paul Keim, a microbiologist at Northern Arizona University in Flagstaff. “A single bacterium can cause disease in mice. It’s hard to get much more virulent than that.”
The genetic makeover that led to the modern plague is thought to have occurred relatively recently in evolutionary history, anywhere from 1,500 to 20,000 years ago. But last month, a discovery was announced that could extend the history of the plague all the way back to a time before humans. George Poinar Jr., a biologist at Oregon State University in Corvallis, found that a 20-million-year-old flea encased in amber has a plague-like bacterium on its proboscis that could be an ancestor of Y. pestis. While a definitive identification of the bacterium hasn’t been made — and may not even be possible — an ancient ancestor of the Black Death could help reveal the earliest steps in a tortured evolutionary path, and perhaps help pinpoint at what point the most deadly changes occurred.
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Now researchers are beginning to reveal a surprising genetic history of the plague. A rash of discoveries show how just a small handful of genetic changes — an altered protein here, a mutated gene there — can transform a relatively innocuous stomach bug into a pandemic capable of killing off a large fraction of a continent.
The most recent of these studies, published in June, found that the acquisition of a single gene named pla gave Y. pestis the ability to cause pneumonia, causing a form of plague so lethal that it kills essentially all of those infected who don’t receive antibiotics. In addition, it is also among the most infectious bacteria known. “Yersinia pestis is a pretty kick-ass pathogen,” said Paul Keim, a microbiologist at Northern Arizona University in Flagstaff. “A single bacterium can cause disease in mice. It’s hard to get much more virulent than that.”
The genetic makeover that led to the modern plague is thought to have occurred relatively recently in evolutionary history, anywhere from 1,500 to 20,000 years ago. But last month, a discovery was announced that could extend the history of the plague all the way back to a time before humans. George Poinar Jr., a biologist at Oregon State University in Corvallis, found that a 20-million-year-old flea encased in amber has a plague-like bacterium on its proboscis that could be an ancestor of Y. pestis. While a definitive identification of the bacterium hasn’t been made — and may not even be possible — an ancient ancestor of the Black Death could help reveal the earliest steps in a tortured evolutionary path, and perhaps help pinpoint at what point the most deadly changes occurred.
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